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Integrated Weed Control Project- Biological Control-
Jennifer AndreasIntegrated Weed Control Project Director
[email protected](206) 205-3135
What is Biocontrol?The intentional use of one living organism to control/suppress another organism, such as WEEDS
Caesar, USDA ARS; bugwood.org
Nematodes
Piper, WSU; bugwood.org
Pathogens
Healing Hooves
Mammals
WSU Extension
Insects
Integrated Weed Management
• Decision-making process
• Strategy for effective weed suppression
• Ecologically-based
• Combination of weed control methods– physical, cultural, chemical, biological
Advantages• Safe – USDA APHIS approves biological
control agents before introduction into U.S.
• Ecologically desirable – herbicide alternative
• Insects are mobile
• Long-term solution
• Cost effectiveWSU Extension
• Long time to make impact
• Subject to predators
• May not establish at some sites
• Very slow approval of new agents
• No eradication
Limitations
Predatory mite
Predatory insect
dinosaurtheory.com
• Established weed infestations
• Remote, inaccessible, less disturbed areas
• Areas not controlled by other means
• Environmentally sensitive sites
When to use biocontrol?
Dargatz, Jefferson CNWCB. WA
WSU Extension
• Small or new infestations
• Highly disturbed areas
• Roads or traveled paths
• Areas unfavorable for insect
• On weeds with no approved agents
When NOT to use biocontrol?
Schwarzlaender
Mazerolle, Air
Mazerolle, Air
Knapweeds
WSU Extension
Spotted knapweed(Centaurea stoebe spp.micranthos)
Diffuse knapweed(Centaurea diffusa)
Meadow knapweed(Centaurea pratensis)
WSU ExtensionWSU Extension
- spread by seed- ↑ soil erosion- ↓biodiversity- ↓quality forage
WSU Extension
Knapweed Biocontrol Agents
WSU Extension
Adult
Larinus obtusus- seed-head feeding weevil- attacks spotted, meadow &
diffuse - currently best agent for meadow- ↓ seed production
WSU Extension
Larva consumes seeds
Adults devouring diffuse knapweed
Larinus minutus- seed-head feeding weevil- attacks diffuse, spotted & meadow - strong impact on diffuse in eastern WA- adults can defoliate plants- ↓ seed production
Success with Larinus minutus !• diffuse knapweed reduced dramatically
Before biocontrol agent release
After biocontrol agent release
WSU Extension WSU Extension
Knapweed Biocontrol Agents
- root-feeding weevil- attacks spotted & diffuse- ↓ biomass & density- can kill plants - good success in
Montana with L. minutus& root weevil
Cyphocleonus achates
WSU Extension
WSU Extension
Larva Larval root damage
Adult
Additional Knapweed Agents
Chaetorelliaacrolophi& Terellia virens- seed-feeding flies- attacks spotted & diffuse
- prefers cool, wet sites
Bangasternus fausti
- seed-feeding weevil- attacks diffuse & spotted
- prefers hot, dry environments
Sphenopterajugoslavica
- root-feeding beetle- attacks diffuse, maybe spotted
- prefers hot, dry environments
Agapeta zoegana- root-feeding moth- attacks spotted & diffuse- impact unknown
Seed-feeders Root-feeders
Rees, USDA ARS; bugwood
Nez Perce Biocontrol Center, ID; bugwood.org
USDA APHIS PPQ; bugwood
USDA APHIS PPQ; bugwood.org
USDA APHIS PPQ; bugwood.org
Adult lays eggs in seed-head
Purple loosestrife
- herbaceous perennial- aquatic, wetland sites- displace native vegetation- degrades wildlife habitat &
hunting/ fishing areas- ↓ water flow
Lythrum salicaria
Agriculture and Agri-Food Canada;.bugwood.org
WSU Extension
Purple Loosestrife Biocontrol
WSU Extension
Beetles skeletonized loosestrife in Pierce County
WSU Extension
Mating adults
Eggs Larva
Galerucella calmariensis / G. pusilla- foliage-feeding beetles- highly effective - larvae & adults devour foliage- do not like tidal-influenced waters
Purple Loosestrife Biocontrol
Piper, WSU; bugwood.org
Coombs, ODA; bugwood.org
Larva mining flower-head
AdultCoombs, ODA; bugwood.org
Schwarzlaender, UI
Larva mines root
Adult
Hylobius transversovittatus- root-feeding weevil- best combined with leaf beetles- kills small roots in 2 years with
several larvae- difficult to collect
Nanophyes marmoratus- bud/ flower-feeding weevil- outcompeted by leaf beetles- ↓ seed production
Scotch Broom
WSU Extension
Coombs, ODA
Adult lays eggs into developing seedpod
Larva consume developing seed
Coombs, ODA; bugwood.org
Adult
Cytisus scoparius- perennial shrub- displace forage & native
species- impacts timber, rangeland
Exapion fuscirostre- seed-feeding weevil- widespread- ↓ seed production
Bruchidius villosus- seed-feeding bruchid- ↓ seed production up to
90%
Tansy Ragwort
Senecio jacobaea- biennial, unless
mowed/cut- toxic to cattle & horses
Lee, San Juan County Noxious Weed Board
Lee, San Juan CNWCB
WSU Extension
Tansy Ragwort Biocontrol
WSU Extension
USDA ARS EBCL; bugwood.org
WSU Extension
WSU Extension
Coombs, ODA Adult feeding holes
Larva mining in leaf
Adult
Longitarsus jacobaeae- root-feeding flea beetle- excellent agent- widespread- Italian & Swiss strains
Coombs, ODA; bugwood.org
Adult
Tansy Ragwort Biocontrol
WSU Extension
Larva consuming seeds
Tyria jacobaeae (cinnabar moth)- foliage-feeding moth- effective in large numbers but
plants are often able to flower- non-target concerns
Botanophila seneciella- seed-feeding fly- widespread
Coombs, ODA; bugwood.org
Adult
WSU Extension
Larvae consuming foliage
R. Lee, San Juan
St. JohnswortHypericum perforatum
WSU Extension
Rees, USDA ARS; bugwood.org
• 1 million hectares in northern California infested in 1944
- perennial, rhizomatous- causes sensitivity to sun- poster child for biocontrol success- now considered mainly a roadside or wasteland weed
St. Johnswort Biocontrol
Chrysolina spp.- foliage-feeding beetle- poster child for biocontrol success!
Rees, USDA ARS; bugwood.org
Harris, AAFC
Rees, USDA ARS; bugwood.com
Eggs
Larvae
Adult
USDA EBCL; bugwood.org
Monument to beetle (and researchers) in California, celebrating success
St. Johnswort Biocontrol
Rees, USDA ARS; bugwood.org
larvae
Adult moth
Rees, USDA ARS; bugwood.org
Adult beetle
Larva mining root
Aplocera plagiata- foliage-feeding moth- success unknown- difficult to collect in large
numbers
Agrilus hyperici- root-boring beetle- success unknown- difficult to collect in large
numbers
Rush Skeletonweed
Chondrilla juncea- long-lived herbaceous perennial- spread by seed & vegetative regrowth- over 404,000 ha in Washington- competes with crop plants- latex hinders crop production- displaces desirable forage
Piper, WSU; bugwood.org
Dewey, Utah State U.; bugwood.org
Rush Skeletonweed BiocontrolEriophyes chondrillae- gall-forming mite- most effective agent- ↓ plant vigor / stunts plants- ↓ seed production- kills seedlings
Puccinia chondrillina- rust fungus- effective- ↓ seed production- ↓ plant vigor- can kill seedlings
Piper, WSU; bugwood.org
Piper, WSU; bugwood.org
Turner, USDA ARS; bugwood.org
Rush Skeletonweed BiocontrolBradyrrhoa gilveolella- root-mining moth- can kill above-ground tissue- establishment questionable- may be available for trials
Cystiphora schmidti- gall midge (fly)- effective- can kill rosettes and stems- ↓ plant vigor- ↓ seed weight & viability
Piper, WSU; bugwood.org
USFS
Canada Thistle
Urophora cardui- stem-galling fly- ↓ plant vigor- works in conjunction with plant
competition
Cirsium arvense- creeping perennial- ↓ forage- competes with crops
The Nature Conservancy
University of Wisconsin
Oregon State University
WSU Extension
Adult
Larva inside plant create gall
WSU Extension
Rees, USDA ARS; bugwood.org
Bull Thistle
Cirsiumvulgare
Shepard, USFS; bugwood.org
Colquhoun; Oregon State U
Urophora stylata- seed-feeding fly- ↓ seed production
WSU Extension
- biennial- prevalent in heavily disturbed sites
Harris, AAFC; bugwood.org
Larvae consume developing seeds
Adult
WSU Extension
Additional Biocontrol
• Biocontrol agents may be available in your area for:– gorse– bindweed– puncturevine– saltcedar– Mediterranean sage
• Class A – must be controlled in Washington
WSU Extension’s Role• State-wide program
• Provide biocontrol agents free of charge to land managers
• Education to land managers
• Expertise and on-site recommendations
Connett, UI; bugwood.org
